So i finally figured it out with a sm465, a np205, 4.56 gears and 39 inch tires i will have a 58.63 crawl ratio. Is this good? should i look into getting lower gears? I have no idea if the is anywhere near good. any one running a simmilar setup? I dont really care about highway speed, as it will be only on the road to anf from the trails. Thanks guys
CK5
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My Crawl Ratio
- Thread starter skidpan
- Start date
loafer
1/2 ton status
6.55x1.98x4.56=59.1
stallion85
1/2 ton status
Here is mine with 3.73's! The SM465 makes a world of difference....I would say that your crawl ratio could def benefit with the addition of the doubler. In all my experience with the SM465 super low crawl numbers I have felt it's good and bad. If you throw a doubler in there you could drive your rig up a straight ledge without even touching the throttle. As of right now my rig will stall pretty easily on the technical stuff and that's with FI added, it was worse with a carb of course.
If you don't have FI I would highly recommend it! I think your crawl ratio is good considering that someone with an auto and a doubler would be putting around the same numbers if not less....
If you don't have FI I would highly recommend it! I think your crawl ratio is good considering that someone with an auto and a doubler would be putting around the same numbers if not less....
I am so confused...Did I do this correctly?
stallion85
1/2 ton status
looks right to me.....
79chevyk10
1/2 ton status
It is my understanding that a torque convertor is a x2 multiplier on crawl ratios.?
stallion85
1/2 ton status
Could be right, I know nothing about transmissions......I do know that there is some wicked wheel spin with the 465 in 1st and the xfer case in low. Torque on demand
79chevyk10
1/2 ton status
I hear ya, that granny low first gear is really nice. I have not doubled yet but plan on it in the near future, but one thing I really love about an auto trans is that torque convertor, no stalling, helps with poor tcase/trans gearing. My motor just luggs until the torque convertor flash point and pops right up the obsticle. Although compression braking stinks with an auto without a doubler, you have to hit the torque convertor flash point before you get engine braking, causes me to use my brakes more than I want out on the trail.
Alright, here comes the really dumb question, the crawl ratio is 70 something revolutions of "Crank, driveshaft, what???" to one revolution of "wheel, what??"
79chevyk10 said:
That's the generally accepted number. I have the same drivetrain combo as you skidpan except i'm running 42's. I rarely find that i need any lower gearing around here. On some of the more technical, steep stuff, I have wanted a lower gear to try and creep it but usually a little throttle will solve that. Believe me, unless you are doing real slow technical rockcrawling/trailriding, you will be fine with your current gears.
theperfectgarage
1/2 ton status
I would want lower gears with that setup, but it depends what you do with your truck. Crawling in the Arizona rocks your gears would be too high. IMO.
Hey skidpan,
Sorry to hijack for a minute there...Anyway, I have a sm465/np 205 and 4.56 gears with 35" tires...I would like bigger tires so I can actually go faster that 65 on the freeway, but as far as crawling goes, in 4lo I can mash the gas and go almost nowhere...in fact on several occasions, I just turned to my girlfriend and had a conversation while the tractor (Blazer) rolled up the hill.
Sorry to hijack for a minute there...Anyway, I have a sm465/np 205 and 4.56 gears with 35" tires...I would like bigger tires so I can actually go faster that 65 on the freeway, but as far as crawling goes, in 4lo I can mash the gas and go almost nowhere...in fact on several occasions, I just turned to my girlfriend and had a conversation while the tractor (Blazer) rolled up the hill.
79chevyk10 said:
that's good news to me! is this really truth? what exactly is a crawl ratio measuring - practical application?
theperfectgarage
1/2 ton status
Hey Colby, it's just the " combined lowness factor " of your gears, ( tranny, t-case, doubler and diffs ) . A 80 to one crawl ratio creeps slower at a givin rpm then say a 50 to one ratio. BTW, engineers just refer to it as the " CLF " ratio.colbystephens said:
6.55 x 1.96 x 4.56 = 58.44:1
That's the exact combo I currently run and on 39.5's too. I didn't feel any compelling need for a deeper crawl ratio even in Moab...but the 6.2 lugs extremely well.
Even so I'm almost done putting my next combo together. NV4500/203/205
5.61 x 1.96 x 2.01 x 4.56 = 100.78:1
600 engine rpm = 6 tire rpms. Or roughly 61 feet per minute at idle with 39.5's. (.69 mph)
Rene
That's the exact combo I currently run and on 39.5's too. I didn't feel any compelling need for a deeper crawl ratio even in Moab...but the 6.2 lugs extremely well.
Even so I'm almost done putting my next combo together. NV4500/203/205
5.61 x 1.96 x 2.01 x 4.56 = 100.78:1
600 engine rpm = 6 tire rpms. Or roughly 61 feet per minute at idle with 39.5's. (.69 mph)
Rene
6.55 x 2.08 x 4.10 = 55.8584
Hehe..
6.55x1.96x2.0x5.13= 132.3:1
6.55x1.96x2.0x5.13= 132.3:1
0.73:1...
Rene
Rene
OD would do me no good. Trailer queen only.
zero cool
1/2 ton status
KidJethro said:Hehe..
6.55x1.96x2.0x5.13= 132.3:1
6.56x4.3x4.56 = 128.6:1
That's just fine for my 37's.
If I had OD, I'd be running 5.89's instead of 4.56's...
Check out http://www.grimmjeeper.com/gears.html if you want to see how different tranny/tcase/axle gear and tire combinations work together.
